On known machines for cartoning groups of bottles, such as the type described, for example, in U.S. Pat. No. 5,148,654, a group of bottles is fed along a packing path and eased onto a central portion of a flat cardboard blank, which is fed, parallel to the path, underneath and in time with the group. Once the group rests completely on the blank, the blank is folded against the group to define a package enclosing the group.
In addition to the central portion, the blank also comprises two first wings extending from the front and rear ends of the central portion; and two lateral portions adjacent to and on opposite sides of the central portion, and each having two second wings extending from the front and rear ends of the lateral portion. The blank is fed along the packing path with the central portion and the lateral portions aligned with one another before being folded crosswise to the packing path.
To fold the blank, two folding bodies are fed along the packing path in time with the assembly defined by the blank and the product and respectively in front of and behind the assembly in the traveling direction along the packing path.
Each folding body comprises a first and a second differently inclined folding edge, and is rotated about an axis crosswise to the packing path so that the first folding edge folds a respective first wing through a given angle of less than 90.degree., and the second folding edge folds respective second wings through 90.degree..
As the assembly is fed along the packing path, the two lateral portions are then engaged by fixed folding edges and folded 90.degree. onto the product and with respect to the central portion; and, once the two lateral portions are folded, the fixed folding bodies release the assembly, which is then engaged by spring-activated retaining edges for keeping the first wings folded at said given angle with respect to the central portion of the blank. In this position, the first wings are gummed and then finish-folded to 90.degree. against the product so that the respective assembly contacts the previous assembly and, later, the next assembly.
The spring-activated retaining edges are particularly complex and, therefore, expensive, and do not always ensure correct positioning of the first wings, particularly at the high traveling speeds of the assemblies on modern bottle cartoning machines capable of producing up to 100 packages a minute.
Moreover, when released by the folding bodies, the assembly is no longer effectively retained at the front and rear, so that, as a result of inevitable vibration induced as it travels at relatively high speed along the packing path, the group of bottles is subjected to severe mechanical stress.